192 LIFE OF surface of the earth became no less the object of his investigation than the fiery fluid, or petrified form of the planet and its outer form. With the infusoria he begins his account of the animal kingdom, and with the microscopic plants, as an entire perfect plant, the circle of vegetable life. Humboldt was assisted in Ms general investigations of this organic world by the most distinguished contem- poraries, who revealed the secrets of the smallest space by means of the microscope, and discovered life, mo- tion, and repetition of the universal Oosmodian con- ditions of existence in every vegetable or animal organization invisible to common eyes. Organic life is active everywhere on the surface of the earth, in its precipices and its atmospheric altitudes; the great ocean contains minute microscopic life far into the polar circles of the arctic ocean. It has been proved by direct observation, that cc in the eternal night of -oceanic depths/* as BCnmboldt expresses himself, more animal than vegetable life is developed, while on terra, jirm>ciy the vegetable principle prevails ; yet the bulk of the latter far exceeds that of the former, although there is less land than sea. Modern naturalists be- lieve they have discovered infusoria in the air. Hum- boldt considers this discovery still doubtful, but not impossible; he thinks that just as well as it has been proved that pine pollen falls from the atmo- sphere, ifc is possible thai little infusoria may be raised upwards in vapour, and be retained floating in the air for some time.* Ehrenberg has also discovered that the misty dust rain which clouds the atmosphere near the Cape Verd islands, 380 leagues from the African coast, consists of the remains of eighteen different silicious, polygastric infusoria. Humboldt classified plants and animals first, accord- ing to their social or their isolated character. In Ms * Even in portions of melted ice floating in round pieces in a latitude of 78° 10' more than fifty kinds of silicious polygastria, were ibaiid, as well as coscinodisfcs with, their green OTraries, beings there- fore capable of supporting life in the extreme of cold.